An outboard motor for a watercraft is mounted to the stern of the watercraft. The outboard motor is typically pivotable about a vertical axis to steer the boat, and also about a horizontal axis to adjust trim/tilt angles.
Implementation of a steering system for an outboard motor can have various drawbacks. For example, a linear actuator, whether hydraulic or electromechanical, requires space well beyond a steering pivot axis to accommodate a driving member, such as a piston, to mount and move rectilinearly. A mechanical system, e.g., a cable-driven steering system, is limited in power output and takes up space in the watercraft between a steering wheel and the outboard motor. A rotary hydraulic actuator has many parts, resulting in complexity, more space occupied, and increased maintenance costs.
An example of an outboard motor steering and adjustment system is described in U.S. Pat. No. 8,840,439 (“the '439 Patent). The '439 Patent includes hydraulic rotary actuators for both steering and trim/tilt. In particular, the hydraulic rotary actuator includes central shaft having splined disks and containing a piston having splined teeth, the splined disks and teeth interacting to translate axial piston movement into rotation when pressurized fluid is applied to one side of the piston. This type of steering and adjustment system is large and includes many parts, including several hydraulic hoses that are fed from the watercraft.
The present disclosure is directed to overcoming one or more problems of the prior art, including excessive space and weight, frequent and expensive maintenance, complicated installation, feedback and vibration through the steering wheel during use, and low energy efficiency. Likewise the present disclosure is directed to providing improved functionality, including redundancy and supplemental power for a steering actuator.